OBJECTIVES: 1. We plan to continue research on visual pigments of vertebrate and invertebrate retinas. Microspectrophotometry of portions of retina and single receptors will be combined with other techniques to further investigate visual transduction and physiology. 2. The biochemistry of photoreceptor membranes with special emphasis on experiments with rod and cone receptors where results may be applied to human visual physiology will be continued. The orientation, rotation, spectral, and ultrastructural changes in these receptor membranes and molecules will be investigated, using biophysical methods. 3. We feel strongly that the combination of microspectrophotometry and ultrastructural research with the electron microscope will lead to useful techniques for the study of eye diseases. 4. Work on insect visual systems already in progress will be continued because these systems offer models for some of the most fundamental processes in vision, including that of humans. The insects are especially useful due to their availability, variety of visual pigments, and membrane processes which will be studied with standard methods in addition to microspectrophotometric and electron microscope techniques. 5. The biochemistry of extracted molecules from vertebrate and invertebrate visual receptor membranes will be further investigated using classical, as well as new methods, with emphasis on the interaction of normal and analog chromophores with visual pigment proteins and lipids.